Sencore Transistorized Harmonic Generator

[LucifersTrip]

I thought some may get a kick out of this one. I just picked this up recently with the intent on using it for an enclosure, then had second thoughts.





The batteries and their contacts are of course corroded/oxidized and one connection has been disconnected. It's funny, you can see the 25 cents price on the battery.

I have since cleaned it up and re-soldered the disconnected wire.

Unfortunately, I have no idea how to test this, so if anyone can help, please do. I do have an oscilloscope if that would help....or maybe I can "work towards front end until defective stage is found".

Btw, the cap is .47uF and the transistor is a 2N406 germanium.

[nexekho]

I personally would just ID all the parts and then build it on a breadboard or something so you can better understand how it works when it isn't old.

Also: AWESOME FIND!

[petemoore]

  Guess is that it is an oscillator/source, for injecting audio into the output, before the output...working toward the input, stage by stage to find the loss-point.

[LucifersTrip]

Yes...it seems it's basically an audio probe.

I just connected it to the input jack going straight into my amp and it does generate a high pitch tone, which does increase in volume as I turn  the knob to max.

[nexekho]

What does the switch in the bottom right do?  I'd guess it changes the frequency used but I'm not sure.

[toneman]

single transistor colpits oscillator??

[PRR]

ALL the instructions are ON it.

It's a buzzer. Put a finger on an audio stage, it buzzes. Except this has a different pitch and tone than a wall-power buzz, so's you know the signal gets through.

Or not.

Which is A Clue.



Any interesting electronics is a chain of stages. Repair-profit electronics often comes to the bench "dead". Yet it lights-up, or if you stick a finger in you jerk (has power). Probably just-one stage has failed. But which one??

Inject tone to the final stage. If the speaker (or TV screen, VU meter, disk cutter) buzzes, the last stage works. Move to the stage before. Since most stages amplify, you should get a bigger BUZZ. Move to the stage before, etc.

In this case, at step 3 we get nothing. First, the example shows a radio, and that stage is an "IF" stage. Put the tester on the "IF-RF" position. But you's an audio guy so you'll usually stay in "Audio" mode. (If you are in a radio and unsure if you are poking audio or IF/RF stage, try both.)

[LucifersTrip]

Yes, as I wrote in my first post "or maybe I can work towards front end until defective stage is found."

But, thanx much for the pic & somewhat clearing up how to do that.  You're saying that if I inject a tone and the stage works, I will get some sort of buzz (or did you use that figuratively?).

What is the min/max output for? simply to increase the volume of the buzz?

I actually thought this was more complicated...that I would inject a tone (which I would have previewed on an oscilloscope), then look at the output it would create through one of the stages....and  adjust something until I got the most pure (closest to the original injected signal) output.

[rnfr]

its just a simple tone generator!  very handy for debugging.   you don't have to sit there with the guitar on your lap!

[LucifersTrip]

yeah, exactly!  though, there's probably a less valuable one I could use...hahah

Btw, if for any wacko reason someone wants to do a schematic or layout and wants more pics, just ask.

[pinkjimiphoton]

that is freekin' cool lu!!  nice find. i love the name...lol

it sounds like just a test tone generator...they usually put out sine or square waves so you can audio probe thru the stages in amps and stuff. you literally work your way back from output to input, without the "one finger" test that jack darr used to use.

i bet if ya replace the caps, it'll be a really handy tool, especially with an oscope..too cool bro!

[PRR]

> I will get some sort of buzz (or did you use that figuratively?). What is the min/max output for? simply to increase the volume of the buzz?

In your words: "it does generate a high pitch tone, which does increase in volume as I turn  the knob to max."

> thought this was more complicated...  adjust something until I got the most pure

No, nothing that fancy.

It's a CHEAP controllable signal. Not pretty, but distictive and useful.

> the "one finger" test that jack darr used to use.

Yup, but less risk of shock, and no confusion with finger/electrical buzz because the pitch/timbre is very different.

The battery holder has to be cleaned. The wax-cap may be bad from old age. Go ahead and put two good C-cells in it. It will probably run 5 months 24/7, or 3 years of 30hr/week 50wk/yr bench duty. And battery power avoids an additional way of getting crossed with power line when poking inside sick amps.